diff --git a/lib/facter/systemd.rb b/lib/facter/systemd.rb
index 9a2086f..4061c59 100644
--- a/lib/facter/systemd.rb
+++ b/lib/facter/systemd.rb
@@ -1,58 +1,61 @@
 # Fact: systemd
 #
 # Purpose:
 #   Determine whether systemd is the init system on the node
 #
 # Resolution:
-#   Check the name of the process 1 (ps -p 1)
+#   Check if the service_provider fact is systemd
 #
 # Caveats:
+#   If you override the service provider then it will return false, even if the
+#   underlying system still is systemd.
 #
 
 # Fact: systemd_version
 #
 # Purpose:
 #   Determine the version of systemd installed
 #
 # Resolution:
-#  Check the output of systemctl --version
+#   Check the output of systemctl --version
 #
 # Caveats:
 #
 
 # Fact: systemd_internal_services
 #
 # Purpose:
 #   List all systemd internal real services + their state
 #
 # Resolution:
-#  Check the output of systemctl --version
+#   Check the output of systemctl --list-unit-files systemd-* and parse it into
+#   a hash with the status
 #
 # Caveats:
 #
 Facter.add(:systemd) do
   confine :kernel => :linux
   setcode do
     Facter.value(:service_provider) == 'systemd'
   end
 end
 
 Facter.add(:systemd_version) do
   confine :systemd => true
   setcode do
     Facter::Util::Resolution.exec("systemctl --version | awk '/systemd/{ print $2 }'")
   end
 end
 
 Facter.add(:systemd_internal_services) do
   confine :systemd => true
   setcode do
     command_output = Facter::Util::Resolution.exec(
       'systemctl list-unit-files --no-legend --no-pager "systemd-*" -t service --state=enabled,disabled,enabled-runtime,indirect'
     )
     lines = command_output.lines.lazy.map { |line| line.split(/\s+/) }
     lines.each_with_object({}) do |(service, status, *), result|
       result[service] = status
     end
   end
 end